Low water control for steam boilers



' E. -w. LOESSER 2,137,880

LOW WATER CONTROL FOR STEAM BOILERS Filed June a, 193'! 2 Sheets-Sheet 1 w. QR fimw N 3 Nov. 22, 1938.

. gr; m mm M o. Q 5% N\ M u f 1 /1 k.\ r Q m g n \w w 3 Mm n nmm H 1Q m fim e p 8 p .w\ K x Q ATTORNEY.

Nov. 22; 1938.

E. w. LOESSER LOW WATER CONTROL FOR STEAM BOILERS 2 Shts-Sheei 2 Fi led June 3, 193'? INVENTOR. finasfllfzaesser,

- ATTORNEY.

Patented Nov. 1938 UNITED ,srArE-s PATENT OFFICE,

LOW mm mlmon snail ErneetW. museum-mustan Application June 3, i837, sci-n1 No. 146.281 4 Claims. (0!. ecu-s4) to a novel control apparatus of the kind men-.

16 munication with the water compartment oi a' boiler, and a float within said chamber, together with means for both mounting the float for 05- j cillation within the chamber, while at the same time sealing said chamber at the point where the 20 float arm projects exteriorly therefrom; said latter means comprising a metallic bellows so constructed as to be freely flexible, to permit operative swing of the float and its arm, while at the same time being strongly resistant to longi- 25 tudinal contraction and expansion under high or low pressures communicated to the chamber interior, to the end that operative condition of the float is assured at all times, and the operative relation of the exterior end of the float arm to 30 switch means adapted to be controlled thereby is maintained against derangement. 7

Other objects of this invention, not at this time more particularly enumerated, will be understood from the following detailed description 86 oi'the same.-

An illustrative embodiment of th invention is shown in the -accompanying drawings. in

which:-

Fig.1 is-an elevational view of the low water 40 control means operatively mounted in connectionwithabo'ilertobeservedthereby; Fig.2 is a vertical section-through the same, taken on line 2-! in Fla-ga Fig. 3 is an enlargedi'ace view in part, with cover cap of switch compart-.

In in the above-described views, to indicate corre- Referring to the drawings, the float chamber of the apparatus is preferably made in two sections, via. an inner section I. and an outersec- I tion ll,thesamebeingsecuredtogetherbyboite it. The Joint between the sections II and II is sealed by an interposed gasket l3. The-assembled sections provide an'interior closed chamber ll. r

The. float chamber is preferably mounted in 5 connection with the boiler Ii in association with the water level gauge glass flxture it with which the boiler is provided, and to this end suitable pipe flttings connect the bottom portion of the chamber ll with the lower pipe connection I! 10 leading from the boiler II to the lower portion of the cause glass fixture. As shown, thme flttings comprise a T I! which is included in said lower pipe connection l1 and a branch pipe." which extends between said T II and the lower 16 port 2| formed in inner section II of said chamber l4. Similarly, suitable pipe flttings'connect the upper portion of the chamber II with the upper pipe connection 21 leading from the boiler ii to the upper portion oi the gauge glas fixture. As shown, the latter fittings comprise a vertical pipe' 22 which extends from the upper port 23 formed in inner section II of said chamber l4, and to the upper end of which is connected, by

an elbow 24, a branch pipe 25 which extends :5 Q

from the boiler II in such manner that said float chamber is substantially fllled with water when the water in the boiler, and correspondingly in the gauieglas, stands at a normal desired level.

The elite: section H of the float chamber ll is provided with an outer face wall 21, from the exterior side of which projects an annular flange 28. Upon the exterior =0! said face wall 21 is mounted an electric circuit control switch to be hereinafter more particularly described. The switch mechanism is enclosed within a removable cover-cap II which is tei engaged over and suitably secured to said annular flange ll.

Located within the interior of the float chamber ll, so as to be buoyantly supported by the '45 water content thereof, is a float member II, preferablyintheiormoi'aholhwmetallicball, totheetubil oiwhichlssecuredafloatarmn.

'l'henovelmeans for mountingthefloatmem berforoecillationundertherlleandfallofso' -water level withinthe while at -thesametimemaintainingawater-tightseai where theexteriorlyproiecflng portion-attire floater-m extends through the .w'aiteomprlleetbetollewingstructurer A threaded bushing as having an enlarged or flanged inner end 34 is threaded from the inner side outwardly through the face wall 21 of chamber section I I, until its flanged inner end 34 abuts said wall; a sealing gasket 3! being interposed between the wall and said flanged inner end 34. Said bushing is provided with a bore I0 extending axially therethrough, a portion 31 of which is of reduced diameter. Extending into the reduced portion 31 of the bushing bore is the outer neck portion 38 of an internal tubular bellows element 39. Said neck portion 38 is suitably secured and Joined to the bushing 33 so as to provide a leak-proof joint. Said internal bellows element 39 is provided at its opposite end with an inner neck portion 40, within which is mounted an end plug 4|, the same being suitably secured and joined thereto so as to provide a leak-proof joint. Said end plug 4| is threaded to receive the float arm 32, which is suitably secured thereto, preferably by a threaded connection as shown. Said float arm 12 is provided with an extension 42 of reduced diameter which passes through the end plug 4| and thence downwardly through the interior passage of said bellows element 39 and through the outer open end of the internal bushing element 31 and the bore of bushing 33. Preferably said extension 42 terminates in a further reduced extremity to form an actuator finger 43. Surrounding said internal bellows element 38, so as to be disposed in spaced concentric relation thereto, is an external bellows element 44. Secured to and between adjacent ends of the internal and external bellows members "-44 are .endplates 45, these parts being so secured and Joined together, as by brazing, soldering or like means, as to provide leak-proof joints, thus forming intermediate the internal and external bellows elements a closed and sealed annular chamber which is filled with a suitable fluid material L such e. g. as oil of desired viscosity, alcohol, or other liquid.

It will be obvious from the above description that the bellows structure constitutes a flexible connection between the float chamber wall and the float arm which is adapted to readily yield to the movements of the float as it rises and falls in response to changes of water level within the float chamber, thus in eflect, providing the equivalent of a pivotal connection. Owing to the provision of the internal bellows element ll in combination with the external bellows element 44, whereby a closed annular chamber between the two is formed, said annular chamber may be filled with a suitable liquid, so that, although the flexing of the structure freely occurs, the bellows structure is internally braced against undue longitudinal contraction and expansion, which, it allowed to occur might prevent proper movement of the float and proper actuation of the switch mechanism which is operated by float movement. The liquid content of the bellows structure is of especial advantage in bracing the latter against contraction or compression in the event high pressure is developed in the boiler and communicated to the float chamber, for, should the bellows structure be subject to contraction of compression from such cause, it might become so rigid that the float would fail to drop upon abnormal lowering of the water level, and consequently timely operation of the switch mechanism might fall under critical conditions and the desired safety function of the apparatus would be defeated.

Pivotally mounted on a fulcrum stud 44, which 2,1s7,sao

projects from the exterior of the float chamber face wall 11, is a carrier plate 41 upon which is adiustably supported a clip plate 48, the clip arms 4! of which are adapted to embrace and carry a mercury tube contactor switch 50.

Mounted upon bracket lugs 5|, with which the float chamber face wall 21 is provided, is a panel 52 having binding posts 53 and 54. One pole, as N, of the switch 50 is connected, by a flexible conductor 56, to binding post 51, and the other pole, as 51, of switch 50 is connected by a flexible conductor 56' to binding post 54. The cover-cap 29 is provided with suitable coupling means 58 to which may be secured outgoing flexible conduit 59 through which conductors of the electrical circuit to be served by the switch 50 may be led and respectively connected to the binding posts I! and 54. The actuator flnger 43, which extends from the float arm extension 42, is operatively coupled to the pivoted carrier plate 41 by engaging said flnger through a perforation 60 with which said carrier plate is provided.

Assuming the switch 50 operates to normally maintain closed an electrical circuit, such e. g. as that serving the fuel burner and delivery mechanism with which boiler i5 is equipped, then the switch and its carrier is so arranged as to normally incline in a direction adapted to dispose its mercury content of the switch in bridging relation to the pole terminals thereof when the float member II is in an uplifted position as governed by a normal water level condition in the boiler and float chamber. Such uplifted position of the float member 38 swings downward the actuator flnger 43 and down tilts the switch carrier and the switch to such normal closed condition (see Figs. 2 and 3). If water in the boiler and consequently in the float chamber falls below normal desired level, then the float member ll will drop, thereby swinging upward the actuator flnger 43, and consequently thereby uptilting the switch carrier and the switch, so that the mercury content of the latter will move out of bridging relation to the switch pole terminals, thus opening the switch and interrupting the electrical circuit to cause stoppage of fuel burner and delivery operation, until such time as the water in the boiler and float chamber is restored to normal level.

It will be obvious that, if desired, the switch It may be arranged to serve an electric circuit controlling the operation of an electrically driven feed water pump, or which controls an electrically actuated feed water admission valve means, rather than the circuit serving the fuel burnerand delivery means. It will be understood that the float controlled actuating means per se, including the novel laterally flexible but longitudinally braced double walled bellows structure for pivotally mounting the float arm in such manner as to allow its tree end to pro- Ject 'exteriorly from the float chamber for cooperation with mechanism desired to be actuated in response to float movements, may be utilized in many other connections and for many purposes in addition to the specific application thereof as a low water control for boilers. It is therefore intended that the invention is to be viewed broadly as to the float controlled sotuating means per se.

It will be'understood that many widely different embodiments of this-invention could be made without departing from'the scope thereof. It is therefore intended that all matter contained in the above description or shown in accompanying drawings-shall be interpreted as illustrative and not in a limiting sense.

Having now described my invention, I claim:- 1. In a control means having a buoyant float operative in a float chamber, said float being provided with an arm having a free end portion projecting exteriorly from said float chamber for cooperation with mechanism to be actuated by float movement, a laterally flexible double movement, a laterally flexible sealing bellows structure comprising, an internal bellows element having an open outer end and a closed inner end, means to secure the open outer end of said internal bellows element to the float chamber wall and so as to openexteriorly through the latter, said float arm being secured to the closed inner end of said internal bellows element and the free end portion of said float arm passing outwardly through the latter and its outer open end, an external bellows element concentrlc to said internal bellows element and forming therewith an intermediate sealed annular chamber, and a liquid mass fllling said annular chamber.

8. In a control means having a bouyant float operative in afloat chamber, said float bein provided with an arm having a free end portion projecting exteriorly from said float chamber, a double walled sealing bellows structure secured to and between the float arm and a wall of said float chamber, said bellows structure providing a sealed annular space intermediate its walls, a liquid mass fllling said annular space, and an electric circuit control switch means mounted exteriorly of said float chamber and adapted to be opened and closed by float controlled movement of the exterior end portion of said float arm.

4. In a device of the kind described, a float operative within' a float chamber, a float arm, a laterally flexible sealing bellows structure comprising, an internal bellows element having an open outer end and a closed inner end, means to secure the open outer end of said element to the float chamber wall and so as to open exteriorly through the latter, an external bellows element concentric to said internal bellows element and forming therewith an intermediate annular space, a liquid mass fllling said annular space, means to secure the closed inner end of said internal bellows element to said float arm, said float arm having an extension passing outwardly through said internal bellows element exteriorly of said float chamber, and an electric IRNBTW.LO 

